1. Field of the Invention
The present invention relates to a process for preparing binderfree hot briquettes for smelting purposes consisting of iron-containing pyrophorous finely divided solids, in which before the briquetting operation the finely divided solids are blown-through by means of a rising, oxydising heated gas flow and held in a fluidized bed, the gas flow being controlled such that by oxidation of at least part of the metallic iron the temperature of the finely divided solids is increased to about 450.degree. to 650.degree. C., and in which subsequently the finely divided solids are hot briquetted.
2. Discussion of Prior Art
The invention relates furthermore to an apparatus for performing the said process. From DE-PS No. 32 23 205 are known a process and apparatus of this type by means of which more than 4% by weight of metallic iron-containing finely divided solids, as they are deposited in filters for instance during the manufacture of steel according to the oxygen blowing process for the recovery of CO, are fed at a temperature of more than 200.degree. C. to a fluidized bed located directly after the filters.
But in many cases the available space in steel production plants does not allow such an arrangement so that the hot filter dust has to be transported over more or less distances to the hot briquetting apparatus. It also happens quite often that due to operational conditions intermediate storage times have to be accepted. Important transport distances and/or intermediate storage times cause cooling of the filter dusts so that when entering the fluidized bed their temperature is not sufficient and oxidation of the metallic iron does not start at all or only insufficiently.
Further difficulties arise when due to production conditions at different operational modes of the oxygen blowing converter the pyrophoric portion of the filter dust is reduced so that the oxidation of the metallic iron is not sufficient for increasing the temperature of the finely divided solids to briquetting temperature.
In the prior apparatus it is also difficult to uniformly maintain the fluidized behaviour of the finely divided solids and it is possible that there is formed a channel in the fluidized bed. Furthermore, it is difficult to exactly control the dwell time of the solids in the fluidized bed.